Not able to run the subroutine ……..error is coming ……UMAT: illegal (negative) actual void ratio detected
Can anybody help
Hypoplastcity sand model
Related Articles
-
Sand Hypoplasticity calibration
Francisco Mendez||Constitutive Modelling|1 |
Views 851
Good evening, everyone. I find it difficult to apply equations (13) and (14) of Herle’s publication “Determination of parameters of a hypoplastic constitutive model from properties of grain assemblies”. As […] -
-
Modelling TX monotonic compressive test with ABAQUS and SANISAND – not working
Riccardo Zabatta||Constitutive Modelling|6 |
Views 1,238
I am trying to reproduce a TX monotonic, compressive test on a sand by using a 1-element, axisymmetric ABAQUS FE model, assigned to a SANISAND material. For this purpose, I […] -
Combining Hypoplastic-sand and Hypoplastic-clay in one UMAT file
anis kheffache||Constitutive Modelling|0 |
Views 573
Hi everyone, i have combined both Hypoplastic sand and clay umats in one umat ( to use for example in the case of multilayered soil medium made of clay and […] -
MatLab m.file
Ala Aljorany||Constitutive Modelling|6 |
Views 1,884
Hi everyone, I’m trying to simulate a triaxial test by using Matlab, adopting the sand hypoplasticity model with strain softening but so far couldn’t succeed. Would anyone help me with […] -
Non convergence problem in abaqus using hpoeca Clay Hypoplasticity in slope model
Yang Xue||Constitutive Modelling|4 |
Views 693
hello everyone! based on the strength reduction method in clay hypoplasticity, firstly, I used two steps belong to the static_general, the first step is impose a gravity load, and not […] -
General questions on implementation of sand hypoplasticity model with Abaqus umat
Panpan Guo||Constitutive Modelling|5 |
Views 1,227
Dear all, I am a PhD student in Zhejiang University. Recently, I have been working on the simulation of a braced excavation with Abaqus. I want to simulate the soil […] -
Hypo-sand UMAT problem
sobhan abedinnejad||Constitutive Modelling|2 |
Views 1,083
Dear community I have 4 Question in implementation of Hypo-sand Umat in ABAQUS could someone kindly explain? 1. I checked the Umat file from (https://soilmodels.com/download/plaxis-umat-hypoplas-zip/) and i understand this subroutine […]
Who is Online
No one is online right now
Search SoilModels Website
Recent posts
-
Shear modulus degragation 12.5.2022
-
FRIC code for clay hypoplasticity interface 23.4.2022
-
Hypo-umat sand 18.4.2022
-
Hypo-umat sand 18.4.2022
-
Using pore fluid-stress element in SandSand 9.4.2022
-
“Warning LNK4210” – hypoplastic clay UMAT 8.4.2022
-
Prague Geotechnical Days 2022 with Prague Geotechnical Lecture by prof. Cino Viggiani 7.4.2022
-
Micropiles load tests database 26.3.2022
-
DIANA 10.5 new features 10.3.2022
-
Input files for element tests for hypoplastic clay/sand UMAT 6.3.2022
-
Combining Hypoplastic-sand and Hypoplastic-clay in one UMAT file 2.3.2022
-
UMAT code for Unsaturated soil modes 19.2.2022
Recent Comments
- Alireza Lajmiri on Download package of ISA cyclic hypoplasticity for Abaqus
- Baban Bapir on Shear modulus degragation
- Rakshanda Showkat on SANISAND for FLAC3D Download
- HaoRan OUYANG on Using pore fluid-stress element in SandSand
- HaoRan OUYANG on Course “Hypoplasticity for Practical Applications”
- Miracle Dai on Hypo-umat sand
- Kassem Dib on liquefaction simulation with abaqus
- Kassem Dib on liquefaction simulation with abaqus
- Kassem Dib on liquefaction simulation with abaqus
- Kassem Dib on Transient Dynamic analysis (U-P formulation)
- Yifei Sun on matlab driver
- SPARSHA SINDURI NAGULA on SANISAND Abaqus UMAT and Plaxis implementations
- Srinivas Vivek Bokkisa on Modelling TX monotonic compressive test with ABAQUS and SANISAND – not working
- MOHD SAQIB on Modelling TX monotonic compressive test with ABAQUS and SANISAND – not working
- Srinivas Vivek Bokkisa on Modelling TX monotonic compressive test with ABAQUS and SANISAND – not working
- Jesus Mediavilla on DIANA FEA 10.3 new release – special on geotechnics
- Keng-Wit Lim on UMAT code for Unsaturated soil modes
- MOHD SAQIB on Modelling TX monotonic compressive test with ABAQUS and SANISAND – not working
Hi, so I guess you provided illegal (negative) actual void ratio 🙂
Hypoplasticity is porosity-dependent model and proper initialisation of state variables is needed, either through sdvini, or through the initialisation implemented directly in umat routine (this is not available in all umats, depends on what umat you use). For example, in sand hypoplasticity umat
https://soilmodels.com/download/plaxis-umat-hypoplas-tar-gz/
you can initialise void ratio using parameter 16, so sdvini routine is not needed, see
https://web.natur.cuni.cz/uhigug/masin/plaxumat/node5.html
I used the model parameters from the Ex-calibre database for sand hypoplasticity (dobrany) and initial (actual) void ratio as the one before oedometric test (0.996). And I’m getting the error for negative actual void ratio. Am I doing something wrong or there could be other reasons for this error?
Hi Jasmine, to try to find out where is the problem, I suggest you to run umat in element test program first. You can also try different sand model umat (there are more options at SoilModels).
Thank you Professor for your prompt reply. I figured from the .dat file in ABAQUS that the void ratio value given in the sdvini subroutine has not been somehow considered in the analysis, because the value printed is null.
I could run the element tests (triaxial) using the subroutines. But, when I open the input file in ABAQUS and then try to run it, it gives error of void ratio.
Thanks got it……..I am using ABAQUS….Is any documentation is available for ABAQUS………I have checked for plaxis well documented manual is there…..Is it possible check pore water pressure and damping during earthquake (forABAQUS)………Currently I am using UMAT the one available in the link https://soilmodels.com/download/plaxis-umat-hypoplas-tar-gz/ (for abaqus i am using only umat file)
The description on parameters here:
https://web.natur.cuni.cz/uhigug/masin/plaxumat/node5.html
is valid both for Plaxis and Abaqus.
If you want to run undrained analysis, then bulk modulus of water Kw is at parameter 15 and excess pore water pressure at statev 8. The same as in clay model (par7, statev8):
https://web.natur.cuni.cz/uhigug/masin/plaxumat/node6.html
Thank you very much……what is the unit of input and output state variable parameter……….can the model be used for liquefaction assessment …….. any limitation i am thinking of using it……….
in page no 6 of documentation it is written as state variable 8 is not used
Hi, yes, I know it is written, but I kept it for internal purposes, it is used. I will correct it in documentation later on. As for liquefaction, in principle you can use it, but this will be up to you, to calibrate the model using your data and assess predictive capabilities. As for state variables, there are either no units or kPa, but this will also be up to you to go through documentation… Hope the model helps, regards David
thank you very much